Abstract: Abstract: Emasculation is closely associated with corn seed production, which directly affects the quality of corn seed. Mechanical emasculation with high efficiency and quality is taking the place of artificial emasculation, which is of low efficiency and poor quality. In China, mechanical emasculation is far behind developed countries, and the emasculation control system is just at the beginning stage, which restricts the development of the emasculation machines. In view of the above problems, this paper designed a set of emasculation control system, which completed adjustment of emasculation mechanism through the parallel four connecting rods driven by cylinder. In order to ensure the accuracy of the parameters, movement of four parallel connecting rods were analyzed. The hardware of the system mainly comprised a display screen, a control board and a control panel. The control board used ATmega128 chip as the control chip, used the 42GRU-9200TTL models (NPN type) photoelectric sensor to collect corn ear height, used MAX4372T chip to collect drive voltage and current, used Power MOSFET IRF4905 to drive proportional valve and used MAX232 chip to complete serial communication. The screen was used to display and set the system parameters. The control panel was used to complete the switch between manual mode and automatic mode and control the height of emasculation mechanism manually by button operation in the manual mode. In automatic mode, the system got the height of ear of corn by photoelectric sensors. The system's control algorithm was that repeatedly reading all the photoelectric sensor signals at a certain time interval, and then storing the number of occluded of up and down photoelectric sensor for the x set of data, and then making the lifting decision of emasculation mechanism according to the first set of data stored previously, and rising the emasculation mechanism only when continuous Z times lifting decision results is rising. Cylinder's movement speed was determined by the opening of proportional valve, and the PWM duty which is directly proportional to proportional electromagnet finally decides the velocity of cylinder. The system controlled the velocity of cylinder by exporting a certain duty PWM signal to control the opening of proportional valve. The system controlled the movement time of cylinder by outputting PWM signal or not, to control the closing and opening of proportional valve. The final purpose of the system is to control the movement of the emasculation mechanism. After analyzing the movement of four parallel connecting rods, combined with the vehicle operation speed and the characteristics of the hydraulic system, the parameters of the system can be obtained by calculating, and were displayed on screen. Through field tests, we found that when the emasculation machine with the emasculation control system designed in this paper rose, the motion time, displacement and maximum speed of cylinder was 150 ms, 0.007 m, and 0.1 m/s, respectively. When the emasculation mechanism went down, the motion time, displacement and maximum speed of cylinder was 180 ms, 0.007 m, and 0.15 m/s, respectively. The testing results showed that the actual movement of the hydraulic cylinder can meet the design requirements and the parameters were reasonably set, and the efficiency and accuracy can meet the castration emasculation operation requirements.